Image processing device
A method of image processing includes the steps of allocating image data of a document into a plurality of blocks of a predetermined pixel matrix; determining a gradient range exponent and a mean value information for each of the blocks based on the image data contained in each of the blocks; encoding the image data of each pixel of each of the blocks into code data based on the mean value information and gradient range exponent for the respective block so that the code data defines each pixel with fewer gradation levels than the image data; determining whether or not a mutually adjoining block is related to a solid image of a same density relative to a block subject to the encoding process; and executing a run length encoding process for a batch of mean value information, gradient range exponent, and code data based on a run length of adjoining blocks discriminated as related to a solid image of the same density.
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Claims
1. A method of image processing, comprising the steps of:
- allocating image data of a document into a plurality of blocks of a predetermined pixel matrix;
- determining a gradient range exponent and a mean value information for each of the blocks based on the image data contained in each of the blocks;
- encoding the image data of each pixel of each of the blocks into code data based on said mean value information and gradient range exponent for the respective block so that the code data defines each pixel with fewer gradation levels than the image data;
- determining whether or not a mutually adjoining block is related to a solid image of a same density relative to a block subject to the encoding process; and
- executing a run length encoding process for a batch of mean value information, gradient range exponent, and code data based on a run length of adjoining blocks discriminated as related to a solid image of the same density.
2. The method of claim 1, wherein the code data represents four gradation levels.
3. The method of claim 2, wherein the predetermined pixel matrix includes sixteen pixels, and the code data is sixteen bytes per block, which includes average value information of eight bits, a gradation range index of eight bits, and thirty two bits representing pixel information.
4. The method of claim 1, wherein a block is determined to be a solid image when the gradient range exponent divided by the mean value information for a block is less than a predetermined value.
5. The method of claim 4, wherein the predetermined value is less than 2%.
6. The method of claim 1 further comprising the step of setting the gradient range exponent to zero when the gradient range exponent divided by the mean value information for a block is less than a predetermined value.
7. The method of claim 6, wherein the pre determined value is less than 2%.
8. The method of claim 1, wherein the run length encoding process calculates a length of a run of blocks of the same density.
9. The image processing device of claim 1
- wherein the code data represents four gradation levels.
10. The image processing device of claim 9, wherein the predetermined pixel matrix includes sixteen pixels, and the code data is sixteen bytes per block, which includes average value information of eight bits, a gradation range index of eight bits, and thirty two bits representing pixel information.
11. A method of image processing, comprising the steps of:
- allocating image data of a document into a plurality of blocks of a predetermined pixel matrix;
- determining a gradient range exponent and a mean value information for each of the blocks based on the image data contained in each of the blocks;
- encoding the image data of each pixel of each of the blocks into code data based on said mean value information and gradient range exponent for the respective block so that the code data defines each pixel with fewer gradation levels than the image data;
- determining whether or not a mutually adjoining block is related to a solid image of a same density relative to a block subject to the encoding process;
- executing a run length encoding process for a batch of mean value information, gradient range exponent, and code data based on a run length of adjoining blocks discriminated as related to a solid image of the same density;
- storing in a memory unit compress ion data and run length data obtained by the run length encoding process;
- comparing a total value of the run length data and compressed data obtained by the run length encoding process with the mean value information, the gradient range exponent, and the code data of each block prior to the run length encoding process; and
- storing in the memory unit the mean value information, the gradient range exponent, and the code data for each block prior to the run length encoding process when the total value of the run length data and the compressed data obtained by the run length encoding process is greater than a total value of the mean value information, the gradient range exponent, and the code data of each block prior to the run length encoding process based on the comparing result.
12. The method of claim 11, wherein the run length encoding process calculates a length of a run of blocks of the same density.
13. The method of claim 11, wherein a block is determined to be a solid image when the gradient range exponent divided by the mean value information for a block is less than a predetermined value.
14. The method of claim 13, wherein the predetermined value is 2%.
15. An image processing device, comprising:
- an encoding processing unit for allocating image data of a document into a plurality of blocks of a predetermined pixel matrix, determining a gradient range exponent and a mean value information for each of the blocks based on the image data contained in each of the blocks, and encoding the image data of each pixel of each of the blocks into code data based on said mean value information and gradient range exponent for the respective block so that the code data defines each pixel with fewer gradation levels than the image data;
- a discrimination unit for determining whether or not a mutually adjoining block is related to a solid image of a same density relative to a block subject to the encoding process; and
- a run length encoding process unit for executing a run length encoding process for a batch of mean value information, gradient range exponent, and code data based on a run length of adjoining blocks discriminated as related to a solid image of the same density.
16. The image processing device of claim 15, wherein a block is determined to be a solid image when the gradient range exponent divided by the mean value information for a block is less than a predetermined value.
17. The image processing device of claim 16, wherein the predetermined value is 2%.
18. The image processing device of claim 15, wherein the gradient range exponent is set to zero when the gradient range exponent divided by the mean value information for a block is less than a predetermined value.
19. The image processing device of claim 18, wherein the predetermined value is less than 2%.
20. The image processing device of claim 15, wherein the run length encoding process unit calculates a length of a run of blocks of the same density.
21. An image processing device, comprising:
- an encoding processing unit for allocating image data of a document into a plurality of blocks of a predetermined pixel matrix, determining a gradient range exponent and a mean value information for each of the blocks based on the image data contained in each of the blocks, and encoding the image data of each pixel of each of the blocks into code data based on said mean value information and gradient range exponent for the respective block so that the code data defines each pixel with fewer gradation levels than the image data;
- a discrimination unit for determining whether or not a mutually adjoining block is related to a solid image of a same density relative to a block subject to the encoding process;
- a run length encoding process unit for executing a run length encoding process for a batch of mean value information, gradient range exponent, and code data based on a run length of adjoining blocks discriminated as related to a solid image of the same density;
- a memory unit for storing in a memory unit compression data and run length data obtained by the run length encoding process;
- a comparator unit for comparing a total value of the run length data and compressed data obtained by the run length encoding process with the mean value information, the gradient range exponent, and the code data of each block prior to the run length encoding process; and
- means for storing in the memory unit the mean value information, the gradient range exponent, and the code data for each block prior to the run length encoding process when the total value of the run length data and the compressed data obtained by the run length encoding process is greater than a total value of the mean value information, the gradient range exponent, and the code data of each block prior to the run length encoding process based on the comparing result.
22. The image processing device of claim 21, wherein a block is determined to be a solid image when the gradient range exponent divided by the mean value information for a block is less than 2%.
23. The image processing device of claim 21, wherein the predetermined value is 2%.
24. The image processing device of claim 21, wherein the run length encoding process calculates a length of a run of blocks of the same density.
| 4979031 | December 18, 1990 | Tsuboi et al. |
| 5119182 | June 2, 1992 | Tsuboi et al. |
| 5361147 | November 1, 1994 | Katayama et al. |
| 5576845 | November 19, 1996 | Komatsu |
| 4-144485A | May 1992 | JPX |
| 4-145765A | May 1992 | JPX |
| 4-157975A | May 1992 | JPX |
| 4-2200076A | August 1992 | JPX |
| 4-236568A | August 1992 | JPX |
Type: Grant
Filed: Jun 18, 1996
Date of Patent: Sep 8, 1998
Assignee: Minolta Co., Ltd. (Osaka)
Inventors: Shoji Imaizumi (Shinshiro), Takayuki Nabeshima (Toyokawa), Shigeru Moriya (Toyokawa)
Primary Examiner: Kim Yen Vu
Assistant Examiner: Kimberly A. Williams
Law Firm: Burns, Doane, Swecker & Mathis, LLP
Application Number: 8/666,691
International Classification: H04N 1419; H04N 1417; H04N 1415;
